IS THE “U-SIGN” RADIOLOGIC FEATURE OF A POSTERIOR CRUCIATE LIGAMENT TIBIAL AVULSION FRACTURE?

ABSTRACT Objective: By analyzing our cases of posterior cruciate ligament (PCL) tibial avulsion fracture, we noted that a U-shaped image was present in the anteroposterior plain radiographs view of the affected knee, even in cases where the profile view of the knee had been inconclusive as to tibial PCL avulsion fracture, a “hidden” fracture. Therefore, we aimed to investigate whether there was an anatomical correlation between this radiological U sign and the tibial insertion of the PCL and to ascertain the intra- and inter-rater reliability of this sign in clinical practice. Methods: The data of the widths and heights area of the PCL tibial insertion area, and the U sign area were measured and compared to the largest width of the tibia. Two moreover, the reliability and reproducibility of this imaging were analyzed. Results: The areas height of the U-sign area and the anatomical insertion area of the posterior cruciate ligament showed no difference, and both were topographically located in the two central quarters of the proximal end of the tibia. The radiographic assessment showed excellent Kappa agreement rates between interobserver and intraobserver, with high reliability and reproducibility. Conclusion: The U sign is a radiographic feature of PCL tibial avulsion fracture seen on the radiograph AP view, there is a high association between the ratios of the U-sign area height in the X-ray and the anatomical height of the PCL tibial insertion site MRI with the largest width of the proximal tibia. The radiographic U sign showed excellent rates of interobserver and intraobserver agreement with Kappa values higher than 0.8. Level of Evidence IV; Dignostic Studies - Investigating a Diagnostic Test.

Modified Arthroscopic Suture Fixation of Posterior Cruciate Ligament Tibial Avulsion Fracture in the Setting of Multiligament Knee Injury in Teenager

The posterior cruciate ligament (PCL) avulsion fracture is a rare injury and occurs mainly in young patients. The development of arthroscopic techniques and fixation methods has improved the treatment of this entity. This report describes a modified arthroscopic suture fixation of a small tibial avulsion fracture of the PCL. A 17-year-old male, injured in a motorcycle crash, was admitted to the Emergency Department and diagnosed with left knee PCL tibial avulsion fracture, lateral collateral ligament (LCL) femoral avulsion fracture, and patella fracture. The PCL was fixed arthroscopically using a Knee Scorpion and two SutureTapes (Arthrex, Munich-Germany) through of an interlaced configuration at the base of the fragment using a transseptal approach and fixed distally over a cortical button on the anterior cortex. The LCL was repaired with two cannulated screws by a percutaneous approach. At 1 year of follow-up, the fragment was healed with tibiofemoral congruence, and the knee was stable with complete range of motion. The Tegner Lysholm Knee Scoring Scale (TLKSS) was 92.

An Uncommon Trauma: Hoffa's Fracture Associated with Tibial Avulsion Fracture of the Posterior Cruciate Ligament

BackgroundSince Hoffa fractures are usually the result of high-energy injuries, many additional accompanying injuries have been described. This is the first paper representing the lateral condyle Hoffa fracture accompanying tibial avulsion fracture of the posterior cruciate ligament (PCL).Case PresentationA 42-years-old male presented with swelling and instability in his left knee after falling during parachute landing. He was diagnosed with simultaneous Letenneur Type I lateral condyle Hoffa fracture and tibial avulsion fracture of the PCL. He was operated on with a single posterior incision for both fractures. Multiple cannulated lag screws were used for the fixation of the Hoffa fracture, and a buttress plate was used for additional stability. PCL avulsion fracture was fixed with a cannulated screw with a washer. The patient was allowed for full-weight-bearing and range of motion at the sixth week after the operation. No complications occurred during follow-up.ConclusionCare should be taken in terms of additional injuries that may accompany Hoffa fractures. The posterior approach allows easy access to both fractures with a single incision. Using a buttress plate after the fixation of the Hoffa fracture with multiple lag screws provides additional stability.